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Biomedical subjects

D Barnett

Publications and source records attributed to D Barnett.

At least 19 recordsLinked to original sources
PubMed1992

The effect of orthotopic transplantation on total, beta 1- and beta 2-adrenoceptors in the human heart.

1. [125I]-(-)pindolol binding was used to determine beta-adrenoceptor density in homogenate preparations of right ventricular endomyocardial biopsies from 43 non-rejecting patients over the first 13 months following cardiac transplantation. The selective beta 1 subtype antagonist ligand CGP 20712A was used to determine the subtype density in 32 of the patients. Biopsy specimens from 15 donor hearts were used as controls. 2. beta-adrenoceptor density (expressed in terms of fmol mg-1 protein) was increased in the group of transplanted hearts as a whole compared with the donor hearts with respect to total (35 +/- 2 vs 23 +/- 2) and the beta 1 subtype (25 +/- 2 vs 16 +/- 2) whereas the beta 2 subtype and radioligand dissociation constant did not differ. 3. Non-parametric analysis of variance of total receptor density over time revealed significant heterogeneity which appears to be due to a discrete increase in beta-adrenoceptor density during the 4th post operative month. 4. These results indicate that beta-adrenoceptor density is not constant following transplantation. Furthermore, the increase in receptor density following transplantation is due mainly to an increase in the beta 1 subtype without a significant change in the beta 2 subtype.

Adult↗
PubMed1992

Endocrine dysfunction in Kearns-Sayre syndrome.

Kearns-Sayre syndrome (KSS) is a form of mitochondrial myopathy in which specific clinical features, namely progressive external ophthalmoplegia, pigmentary retinal degeneration and cardiac conduction defects, occur. KSS has also been associated with a variety of endocrine and metabolic disorders, in particular short stature, gonadal failure, diabetes mellitus, thyroid disease, hyperaldosteronism, hypomagnesaemia, and bone, tooth and calcification abnormalities. A case is described exhibiting all of these features. A survey of the literature was conducted to determine the prevalence of these conditions among reported cases. Cases with hypoparathyroidism were considered separately to see if they constituted a distinct subgroup with multiple endocrine dysfunction. Short stature was common, being documented in 38% of cases. Gonadal dysfunction before or after puberty was also common (20% of cases) and affected both sexes equally. Diabetes mellitus was recorded in 13% of cases, half of which required insulin. Thyroid disease, hyperaldosteronism and hypomagnesaemia were uncommon but were probably not looked for in many cases. Bone or tooth abnormalities and calcification of the basal ganglia were found both in those with and without hypoparathyroidism. While endocrine and metabolic dysfunction was found more commonly in those with hypoparathyroidism this is likely to be due to increased recognition rather than increased prevalence. No evidence of an autoimmune polyendocrine syndrome including hypoparathyroidism was found.

Child↗
PubMed1991

Human IgE-binding synthetic peptides of bovine beta-lactoglobulin and alpha-lactalbumin. In vitro cross-reactivity of the allergens.

The allergenicity of cow's milk whey proteins, purified by high performance liquid chromatography (HPLC), was examined by the radio-allergosorbent test (RAST) against the sera of children immediately hypersensitive to milk. beta-lactoglobulin and alpha-lactalbumin bound specific IgE in the sera of 63% and 75% of these patients respectively. These allergens were tested for cross reactivity with each other by RAST inhibition. Both inhibited the binding of IgE, in the sera of allergic patients, to the other protein. Two possible determinant peptides, one from beta-lactoglobulin and one from alpha-lactalbumin, were selected by computer prediction of antigenic sites and synthesized by the fluorenylmethoxycarbonyl (FMOC)-polyamide method. The peptides were adsorbed to nitrocellulose discs and used in further RAST studies with sera from the allergic children. Both peptides bound specific IgE in the RAST assay.

Allergens↗
PubMed1991

Hb Cleveland or alpha 2 beta 2(93)(F9)Cys----Arg;121(GH4)Glu----Gln.

Hb Cleveland is characterized by two amino acid substitutions, namely beta 121(GH4)Glu----Gln as in Hb D-Los Angeles and beta 93(F9)Cys----Arg as in Hb Okazaki, and shares with Hb Okazaki a decreased stability, an increase in oxygen affinity, and decreases in Bohr effect and heme-heme interaction. It is the 13th beta chain variant with two substitutions that has been described thus far.

Adult↗
PubMed1990

Self-concept, motivation, and competence among preschoolers from maltreating and comparison families.

Maltreated children are at risk for impaired cognitive and school functioning. In this study, the role that home environment, self-concept, and mastery motivation play in this relation was investigated. Thirty-six preschool children and their mothers, representing three family backgrounds (12 low-income maltreating, 12 low-income comparison, 12 middle-income comparison), were assessed in a preschool/home study. Children from maltreating families scored lower than their peers on several measures of cognitive and physical competence and on ratings of motivation. At the same time, these children significantly overrated their physical competence, and self-ratings of competence and acceptance tended to be higher (and less realistic) than those of their low-income peers. An overall difference in developmental quality of the home environment of maltreating families was largely accounted for by socioeconomic status (SES), but the tendency of these homes to be less clean and safe remained significant even after SES was controlled. Various aspects of the home environment were associated with superior task performance, but not with motivation or self-perceptions. Whereas the general home environment may affect competence, relationship factors implicated in maltreatment may be more important in shaping self-concept and motivation.

Achievement↗
PubMed1990

Relationship of changes in pH and energy status to hypoxic cell fraction and hyperthermia sensitivity.

The relative concentrations of nucleotide triphosphates, creatine phosphate, inorganic phosphate, and pH have been evaluated as a function of tumor volume in a murine fibrosarcoma (FSaII) by 31P NMR spectroscopy. As the tumor volume increased from 60-1250 mm3, the ratio of phosphocreatine to inorganic phosphate systemically decreased. This decrease paralleled a decrease in the ratio of nucleotide triphosphate to inorganic phosphate in the same tumor volume range. The tumor pH as measured by 31P NMR decreased slightly with tumor growth. A pH of 7.17 +/- 0.07 (n = 17) was found for tumors between 60 and 150 mm3, whereas for tumors greater than 900 mm3, a pH of 7.05 +/- .03 (n = 6) was noted. Intermediate size tumors (151-900) had a pH of 7.12 +/- 0.09 (n = 18). The change in tumor energy status with tumor volume inversely paralleled the change in tumor radiobiologic hypoxic cell fraction and suggested a causal relationship between tumor nutrient status and energy status. Tumor thermal sensitivity also increased with tumor volume, suggesting a relationship between pH, energy status, and thermal sensitivity, as has been demonstrated under in vitro conditions. Each NMR parameter was found to correlate significantly with tumor volume independent of the other NMR parameters.

Adenosine Triphosphate↗
PubMed1990

The use of a calcium-channel blocker, nicardipine, for severely asphyxiated newborn infants.

A continuous infusion of nicardipine was given to four severely asphyxiated fullterm infants who were at high risk for adverse outcome and had abnormal cerebral Doppler haemodynamic studies. The heart rate increased in all four infants and mean arterial blood pressure (MAP) fell in three. Two infants had a sudden and marked fall in MAP, together with severe impairment of skin blood-flow and a concurrent fall in cerebral blood-flow velocity. The serum level of nicardipine was less than 40ng/mL in all cases. The use of nicardipine, and possibly other calcium-channel blockers, may be associated with marked hypotension, and if there is no cerebral autoregulation, may cause further cerebral hypoperfusion, so use of these drugs in asphyxiated newborn infants should only be attempted if blood pressure is carefully monitored.

Asphyxia Neonatorum↗
PubMed1990

Value of monoclonal anti-myeloperoxidase (MPO7) for diagnosing acute leukaemia.

The expression of myeloperoxidase (MPO) was studied in 100 cases of acute leukaemia (83 with acute myeloid leukaemia (AML) and 17 acute lymphoblastic leukaemia (ALL) by both a conventional cytochemical method and the immunocytochemical antiperoxidase (APAAP) technique using the monoclonal antibody MPO7. In each case the staining was evaluated by light microscopical examination (percentage of positive cells). Of the 83 cases of AML, 78 (93.9%) were positive for MPO7 compared with 70 (84.3%) by cytochemistry. Antibodies against the myeloid markers CD13 and CD33 were positive in 71 (85.5%) and 70 (84.3%) cases, respectively. Importantly, all cases of ALL were negative for both MPO7 and cytochemical MPO staining even when they were positive for CD13 and CD33. These results indicate that the anti-myeloperoxidase antibody MPO7 is the most sensitive and specific reagent for the diagnosis of AML and should therefore be included in routine immunophenotyping panels.

Antibodies, Monoclonal↗
PubMed1990

Monosomy 7, leukaemia and immunoglobulin heavy chain gene rearrangement.

We describe the haematological findings and clinical course of a 15-year-old male who presented with a spontaneous acute lymphoblastic leukaemia. The lymphoid origin of the leukaemia was supported by cell surface antigen studies and immunoglobulin heavy chain gene analysis. Bone marrow karyotype was simple monosomy 7 and the lymphoblasts expressing the myeloid associated antigen CD 33. Both of these features have been previously shown to indicate a poor prognosis. The findings in this patient support a previous hypothesis that monosomy 7 can arise at the stem cell level.

Adolescent↗
PubMed1989

Laboratory control of immunocytochemistry.

Monoclonal antibody technology is now used in many haematology departments for the analysis and phenotyping of haematological malignancies. Immunocytochemical analysis, in particular the alkaline phosphatase anti-alkaline phosphatase (APAAP) technique is increasing in popularity. This paper describes the findings from the 1st year of an external quality assurance scheme for immunocytochemistry. Initially, there was a wide variation amongst the results received. An improvement was seen over the year with subsequent concordance in the results. This variation could be due to a number of variables within the technique which this report highlights.

Antibodies, Monoclonal↗
PubMed1988

New allergens from hen's egg white and egg yolk. In vitro study of ovomucin, apovitellenin I and VI, and phosvitin.

Three hen egg yolk proteins, apovitellenins I and VI and phosvitin, and one egg white protein, ovomucin, were purified and tested for their ability to bind IgE in the sera of patients hypersensitive to egg. All of the proteins bound IgE from the sera of egg-allergic individuals in the radioallergosorbent test, and they also inhibited binding of IgE to the parent fractions-either egg yolk (apovitellenins I and VI and phosvitin) or egg white (ovomucin). It appears that apovitellenins I and VI are major allergens for some of the individuals tested. This is the first report of the in vitro allergenicity of these proteins.

Allergens↗
PubMed1988

The interleukin-2 receptor and its expression in the acute leukaemias and lymphoproliferative disorders.

The expression of the interleukin-2 receptor (IL-2R) was investigated in a total of 117 cases of acute leukaemia and lymphoproliferative disorder. The results confirm reports that the interleukin-2 receptor can be expressed on cells of myeloid lineage and in cases of Hairy Cell Leukaemia. They extend knowledge of the expression of the IL-2R in cases of lymphoproliferative disorders.

Acute Disease↗